Method and apparatus for dynamic bandwidth provisioning in frequency division duplex systems

ABSTRACT

A method and apparatus are described that provides flexible spectrum usage by using a paired frequency division duplex (FDD) spectrum to enable dynamic access in television white space (TVWS), sub-leased spectrum or unlicensed spectrum, (e.g., industrial, scientific and medical (ISM) bands), in a femto cell environment or the like. Elastic FDD (E-FDD) enables femto cell operation in TVWS, sub-leased spectrum and/or unlicensed spectrum, either simultaneously with licensed spectrum or as an alternate channel to licensed spectrum. E-FDD enables dynamic asymmetric bandwidth allocation for uplink (UL) and downlink (DL) in FDD, and enables variable duplex spacing, (i.e., using FDD with minimum duplex spacing between DL and UL spectrum, or, using hybrid-FDD, (FDD in a time duplexed fashion), when a spectrum gap between the UL and DL spectrum is below a certain minimum threshold. Additionally, the signaling enhancements to implement E-FDD are also provided.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. provisional application No.61/383,181, filed Sep. 15, 2010, the contents of which are herebyincorporated by reference herein.

TECHNICAL FIELD

This application is related to wireless communications.

BACKGROUND

With the ever increasing demand for higher bandwidths, there is animmediate need to provide larger chunks of spectrum to each user toenable convergence of various services and simultaneous use of spectrumby multiple users. Traditionally, spectrum has been statically allocatedto licensed operators. Users served by the licensed operators areprovided small resource blocks in time and frequency. This scheme maynot provide high data rates in the order of 100s of Mbps or Gbps tomultiple users simultaneously.

One of the basic problems of systems today is to let a number of devicesshare a common resource, i.e., the allocated spectrum, in an efficientmanner so as to simultaneously meet all desired performance objectives,such as fairness, low latency, high throughput, spectral efficiency,reasonable overhead, high mobility, fast scheduling and stability.

SUMMARY

A method and apparatus are described that provides flexible spectrumusage by using a paired frequency division duplex (FDD) spectrum toenable dynamic access in television white space (TVWS), sub-leasedspectrum or unlicensed spectrum, (e.g., industrial, scientific andmedical (ISM) bands), in a femto cell environment or the like. ElasticFDD (E-FDD) enables femto cell operation in TVWS, sub-leased spectrumand/or unlicensed spectrum, either simultaneously with licensed spectrumor as an alternate channel to licensed spectrum. E-FDD enables dynamicasymmetric bandwidth allocation for uplink (UL) and downlink (DL) inFDD, and enables variable duplex spacing, (i.e., using FDD with minimumduplex spacing between DL and UL spectrum, or, using hybrid-FDD, (FDD ina time duplexed fashion), when a spectrum gap between the UL and DLspectrum is below a certain minimum threshold. Additionally, thesignaling enhancements to implement E-FDD are also provided.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding may be had from the following description,given by way of example in conjunction with the accompanying drawingswherein:

FIG. 1A is a system diagram of an example communications system in whichone or more disclosed embodiments may be implemented;

FIG. 1B is a system diagram of an example wireless transmit/receive unit(WTRU) that may be used within the communications system illustrated inFIG. 1A;

FIG. 1C is a system diagram of an example radio access network and anexample core network that may be used within the communications systemillustrated in FIG. 1A; and

FIG. 2 shows a plurality of wireless transmit/receive units (WTRUs)within a macro cell and a femto cell;

FIG. 3 shows an example architecture of a macro evolved Node-B (eNodeB)and a home evolved Node-B (HeNB);

FIG. 4 shows an example high-level architecture for a scenario where aHeNB and a WTRU communicate over a single radio access technology (RAT)using an FDD duplex scheme;

FIG. 5 shows an example of moving uplink (UL) and downlink (DL) FDDbands from high spectrum bands to lower spectrum bands;

FIG. 6 shows an example licensed spectrum allocation for UL and DL inFDD;

FIG. 7 shows an example asymmetric assignment of UL and DL spectrumusing elastic FDD (E-FDD);

FIGS. 8A, 8B and 8C show an example dynamic allocation for UL and DLspectrum based on a traffic pattern;

FIG. 9 shows an example dynamic allocation of spectrum in televisionwhitespace (TVWS) in the presence of a wireless microphone;

FIG. 10 shows an example of moving only the UL spectrum from a licensedband to a TVWS band;

FIG. 11 shows an example of aggregating licensed FDD UL and DL spectrumwith a flexible FDD in unlicensed bands.

FIG. 12 shows an example full duplex FDD with a DL spectrum band and aUL spectrum band sufficiently separated;

FIG. 13 shows an example full duplex FDD where a DL spectrum band and aUL spectrum band have minimum frequency separation;

FIG. 14 shows an example half duplex FDD where a DL spectrum band and aUL spectrum band have less than a minimum frequency separation;

FIG. 15 shows an example full duplex FDD with adaptive interferencecancellation;

FIG. 16 shows an example high level modem design to support variableduplex FDD;

FIG. 17 shows an example flowchart for elastic asymmetric bandwidthprovisioning (E-ABP) in elastic FDD (E-FDD);

FIGS. 18A and 18B show an example table that indicates parameters thatneed to be signaling during system acquisition in current femto systemsto enable E-FDD;

FIGS. 19A and 19B show an example flowchart 1900 for dynamic spectrumallocation for E-FDD;

FIG. 20 shows an example call flow to enable elastic-asymmetricbandwidth provisioning (E-ABP) within a cellular network; and

FIGS. 21A, 21B and 21C show an example table comparing traditional FDDand time division duplex with E-FDD.

DETAILED DESCRIPTION

FIG. 1A is a diagram of an example communications system 100 in whichone or more disclosed embodiments may be implemented. The communicationssystem 100 may be a multiple access system that provides content, suchas voice, data, video, messaging, broadcast, etc., to multiple wirelessusers. The communications system 100 may enable multiple wireless usersto access such content through the sharing of system resources,including wireless bandwidth. For example, the communications system 100may employ one or more channel access methods, such as code divisionmultiple access (CDMA), time division multiple access (TDMA), frequencydivision multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrierFDMA (SC-FDMA), and the like.

As shown in FIG. 1A, the communications system 100 may include wirelesstransmit/receive units (WTRUs) 102A, 102B, 102C, 102D, a radio accessnetwork (RAN) 104, a core network 106, a public switched telephonenetwork (PSTN) 108, the Internet 110, and other networks 112, though itwill be appreciated that the disclosed embodiments contemplate anynumber of WTRUs, base stations, networks, and/or network elements. Eachof the WTRUs 102A, 102B, 102C, 102D may be any type of device configuredto operate and/or communicate in a wireless environment. By way ofexample, the WTRUs 102A, 102B, 102C, 102D may be configured to transmitand/or receive wireless signals and may include user equipment (UE), amobile station, a fixed or mobile subscriber unit, a pager, a cellulartelephone, a personal digital assistant (PDA), a smartphone, a laptop, anetbook, a personal computer, a wireless sensor, consumer electronics,and the like.

The communications system 100 may also include a base station 114A and abase station 114B. Each of the base stations 114A, 114B may be any typeof device configured to wirelessly interface with at least one of theWTRUs 102A, 102B, 102C, 102D to facilitate access to one or morecommunication networks, such as the core network 106, the Internet 110,and/or the networks 112. By way of example, the base stations 114A, 114Bmay be a base transceiver station (BTS), a Node-B, an eNodeB, a HomeNode-B, a Home eNodeB, a site controller, an access point (AP), awireless router, and the like. While the base stations 114A, 114B areeach depicted as a single element, it will be appreciated that the basestations 114A, 114B may include any number of interconnected basestations and/or network elements.

The base station 114A may be part of the RAN 104, which may also includeother base stations and/or network elements (not shown), such as a basestation controller (BSC), a radio network controller (RNC), relay nodes,etc. The base station 114A and/or the base station 114B may beconfigured to transmit and/or receive wireless signals within aparticular geographic region, which may be referred to as a cell (notshown). The cell may further be divided into cell sectors. For example,the cell associated with the base station 114A may be divided into threesectors. Thus, in one embodiment, the base station 114A may includethree transceivers, i.e., one for each sector of the cell. In anotherembodiment, the base station 114A may employ multiple-input multipleoutput (MIMO) technology and, therefore, may utilize multipletransceivers for each sector of the cell.

The base stations 114A, 114B may communicate with one or more of theWTRUs 102A, 102B, 102C, 102D over an air interface 116, which may be anysuitable wireless communication link (e.g., radio frequency (RF),microwave, infrared (IR), ultraviolet (UV), visible light, etc.). Theair interface 116 may be established using any suitable radio accesstechnology (RAT).

More specifically, as noted above, the communications system 100 may bea multiple access system and may employ one or more channel accessschemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. Forexample, the base station 114A in the RAN 104 and the WTRUs 102A, 102B,102C may implement a radio technology such as Universal MobileTelecommunications System (UMTS) Terrestrial Radio Access (UTRA), whichmay establish the air interface 116 using wideband CDMA (WCDMA). WCDMAmay include communication protocols such as High-Speed Packet Access(HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-Speed DLPacket Access (HSDPA) and/or High-Speed UL Packet Access (HSUPA).

In another embodiment, the base station 114A and the WTRUs 102A, 102B,102C may implement a radio technology such as Evolved UMTS TerrestrialRadio Access (E-UTRA), which may establish the air interface 116 usingLong Term Evolution (LTE) and/or LTE-Advanced (LTE-A).

In other embodiments, the base station 114A and the WTRUs 102A, 102B,102C may implement radio technologies such as IEEE 802.16 (i.e.,Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000,CDMA2000 1×, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), InterimStandard 95 (IS-95), Interim Standard 856 (IS-856), Global System forMobile communications (GSM), Enhanced Data rates for GSM Evolution(EDGE), GSM EDGE (GERAN), and the like.

The base station 114B in FIG. 1A may be a wireless router, Home Node-B,Home eNodeB, or access point, for example, and may utilize any suitableRAT for facilitating wireless connectivity in a localized area, such asa place of business, a home, a vehicle, a campus, and the like. In oneembodiment, the base station 114B and the WTRUs 102C, 102D may implementa radio technology such as IEEE 802.11 to establish a wireless localarea network (WLAN). In another embodiment, the base station 114B andthe WTRUs 102C, 102D may implement a radio technology such as IEEE802.15 to establish a wireless personal area network (WPAN). In yetanother embodiment, the base station 114B and the WTRUs 102C, 102D mayutilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A,etc.) to establish a picocell or femto cell. As shown in FIG. 1A, thebase station 114B may have a direct connection to the Internet 110.Thus, the base station 114B may not be required to access the Internet110 via the core network 106.

The RAN 104 may be in communication with the core network 106, which maybe any type of network configured to provide voice, data, applications,and/or voice over internet protocol (VoIP) services to one or more ofthe WTRUs 102A, 102B, 102C, 102D. For example, the core network 106 mayprovide call control, billing services, mobile location-based services,pre-paid calling, Internet connectivity, video distribution, etc.,and/or perform high-level security functions, such as userauthentication. Although not shown in FIG. 1A, it will be appreciatedthat the RAN 104 and/or the core network 106 may be in direct orindirect communication with other RANs that employ the same RAT as theRAN 104 or a different RAT. For example, in addition to being connectedto the RAN 104, which may be utilizing an E-UTRA radio technology, thecore network 106 may also be in communication with another RAN (notshown) employing a GSM radio technology.

The core network 106 may also serve as a gateway for the WTRUs 102A,102B, 102C, 102D to access the PSTN 108, the Internet 110, and/or othernetworks 112. The PSTN 108 may include circuit-switched telephonenetworks that provide plain old telephone service (POTS). The Internet110 may include a global system of interconnected computer networks anddevices that use common communication protocols, such as thetransmission control protocol (TCP), user datagram protocol (UDP) andthe internet protocol (IP) in the TCP/IP internet protocol suite. Thenetworks 112 may include wired or wireless communications networks ownedand/or operated by other service providers. For example, the networks112 may include another core network connected to one or more RANs,which may employ the same RAT as the RAN 104 or a different RAT.

Some or all of the WTRUs 102A, 102B, 102C, 102D in the communicationssystem 100 may include multi-mode capabilities, i.e., the WTRUs 102A,102B, 102C, 102D may include multiple transceivers for communicatingwith different wireless networks over different wireless links. Forexample, the WTRU 102C shown in FIG. 1A may be configured to communicatewith the base station 114A, which may employ a cellular-based radiotechnology, and with the base station 114B, which may employ an IEEE 802radio technology.

FIG. 1B is a system diagram of an example WTRU 102. As shown in FIG. 1B,the WTRU 102 may include a processor 118, a transceiver 120, atransmit/receive element 122, a speaker/microphone 124, a keypad 126, adisplay/touchpad 128, a non-removable memory 130, a removable memory132, a power source 134, a global positioning system (GPS) chipset 136,and other peripherals 138. It will be appreciated that the WTRU 102 mayinclude any sub-combination of the foregoing elements while remainingconsistent with an embodiment.

The processor 118 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), aplurality of microprocessors, one or more microprocessors in associationwith a DSP core, a controller, a microcontroller, Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Array (FPGAs)circuits, any other type of integrated circuit (IC), a state machine,and the like. The processor 118 may perform signal coding, dataprocessing, power control, input/output processing, and/or any otherfunctionality that enables the WTRU 102 to operate in a wirelessenvironment. The processor 118 may be coupled to the transceiver 120,which may be coupled to the transmit/receive element 122. While FIG. 1Bdepicts the processor 118 and the transceiver 120 as separatecomponents, it will be appreciated that the processor 118 and thetransceiver 120 may be integrated together in an electronic package orchip.

The transmit/receive element 122 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station114A) over the air interface 116. For example, in one embodiment, thetransmit/receive element 122 may be an antenna configured to transmitand/or receive RF signals. In another embodiment, the transmit/receiveelement 122 may be an emitter/detector configured to transmit and/orreceive IR, UV, or visible light signals, for example. In yet anotherembodiment, the transmit/receive element 122 may be configured totransmit and receive both RF and light signals. It will be appreciatedthat the transmit/receive element 122 may be configured to transmitand/or receive any combination of wireless signals.

In addition, although the transmit/receive element 122 is depicted inFIG. 1B as a single element, the WTRU 102 may include any number oftransmit/receive elements 122. More specifically, the WTRU 102 mayemploy MIMO technology. Thus, in one embodiment, the WTRU 102 mayinclude two or more transmit/receive elements 122 (e.g., multipleantennas) for transmitting and receiving wireless signals over the airinterface 116.

The transceiver 120 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 122 and to demodulatethe signals that are received by the transmit/receive element 122. Asnoted above, the WTRU 102 may have multi-mode capabilities. Thus, thetransceiver 120 may include multiple transceivers for enabling the WTRU102 to communicate via multiple RATs, such as UTRA and IEEE 802.11, forexample.

The processor 118 of the WTRU 102 may be coupled to, and may receiveuser input data from, the speaker/microphone 124, the keypad 126, and/orthe display/touchpad 128 (e.g., a liquid crystal display (LCD) displayunit or organic light-emitting diode (OLED) display unit). The processor118 may also output user data to the speaker/microphone 124, the keypad126, and/or the display/touchpad 128. In addition, the processor 118 mayaccess information from, and store data in, any type of suitable memory,such as the non-removable memory 130 and/or the removable memory 132.The non-removable memory 130 may include random-access memory (RAM),read-only memory (ROM), a hard disk, or any other type of memory storagedevice. The removable memory 132 may include a subscriber identity (ID)module (SIM) card, a memory stick, a secure digital (SD) memory card,and the like. In other embodiments, the processor 118 may accessinformation from, and store data in, memory that is not physicallylocated on the WTRU 102, such as on a server or a home computer (notshown).

The processor 118 may receive power from the power source 134, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 102. The power source 134 may be any suitabledevice for powering the WTRU 102. For example, the power source 134 mayinclude one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion),etc.), solar cells, fuel cells, and the like.

The processor 118 may also be coupled to the GPS chipset 136, which maybe configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 102. In additionto, or in lieu of, the information from the GPS chipset 136, the WTRU102 may receive location information over the air interface 116 from abase station (e.g., base stations 114A, 114B) and/or determine itslocation based on the timing of the signals being received from two ormore nearby base stations. It will be appreciated that the WTRU 102 mayacquire location information by way of any suitablelocation-determination method while remaining consistent with anembodiment.

The processor 118 may further be coupled to other peripherals 138, whichmay include one or more software and/or hardware modules that provideadditional features, functionality and/or wired or wirelessconnectivity. For example, the peripherals 138 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, and the like.

FIG. 1C is a system diagram of the RAN 104 and the core network 106according to an embodiment. As noted above, the RAN 104 may employ aUTRA radio technology to communicate with the WTRUs 102 a, 102 b, 102 cover the air interface 116. The RAN 104 may also be in communicationwith the core network 106. As shown in FIG. 1C, the RAN 104 may includeNode-Bs 140 a, 140 b, 140 c, which may each include one or moretransceivers for communicating with the WTRUs 102 a, 102 b, 102 c overthe air interface 116. The Node-Bs 140 a, 140 b, 140 c may each beassociated with a particular cell (not shown) within the RAN 104. TheRAN 104 may also include RNCs 142 a, 142 b. It will be appreciated thatthe RAN 104 may include any number of Node-Bs and RNCs while remainingconsistent with an embodiment.

As shown in FIG. 1C, the Node-Bs 140 a, 140 b may be in communicationwith the RNC 142 a. Additionally, the Node-B 140 c may be incommunication with the RNC 142 b. The Node-Bs 140 a, 140 b, 140 c maycommunicate with the respective RNCs 142 a, 142 b via an Iub interface.The RNCs 142 a, 142 b may be in communication with one another via anIur interface. Each of the RNCs 142 a, 142 b may be configured tocontrol the respective Node-Bs 140 a, 140 b, 140 c to which it isconnected. In addition, each of the RNCs 142 a, 142 b may be configuredto carry out or support other functionality, such as outer loop powercontrol, load control, admission control, packet scheduling, handovercontrol, macrodiversity, security functions, data encryption, and thelike.

The core network 106 shown in FIG. 1C may include a media gateway (MGW)144, a mobile switching center (MSC) 146, a serving GPRS support node(SGSN) 148, and/or a gateway GPRS support node (GGSN) 150. While each ofthe foregoing elements are depicted as part of the core network 106, itwill be appreciated that any one of these elements may be owned and/oroperated by an entity other than the core network operator.

The RNC 142 a in the RAN 104 may be connected to the MSC 146 in the corenetwork 106 via an IuCS interface. The MSC 146 may be connected to theMGW 144. The MSC 146 and the MGW 144 may provide the WTRUs 102 a, 102 b,102 c with access to circuit-switched networks, such as the PSTN 108, tofacilitate communications between the WTRUs 102 a, 102 b, 102 c andtraditional land-line communications devices.

The RNC 142 a in the RAN 104 may also be connected to the SGSN 148 inthe core network 106 via an IuPS interface. The SGSN 148 may beconnected to the GGSN 150. The SGSN 148 and the GGSN 150 may provide theWTRUs 102 a, 102 b, 102 c with access to packet-switched networks, suchas the Internet 110, to facilitate communications between and the WTRUs102 a, 102 b, 102 c and IP-enabled devices.

As noted above, the core network 106 may also be connected to thenetworks 112, which may include other wired or wireless networks thatare owned and/or operated by other service providers.

Spectrum pooling or aggregation across different contiguous ornon-contiguous bands using a single carrier or multiple carriers may beneeded for efficient use of spectrum resources. Each user may beallocated different time and frequency resource blocks on various bandsacross various carriers, and provide the necessary bandwidth to achievethe required quality of service (QoS) by each user. The various bandsacross different carriers may be licensed bands, unlicensed bands,sub-leased bands, or whitespace bands.

To achieve this kind of on-demand resource allocation across a widespectrum range inclusive of licensed, unlicensed, sub-leased orwhitespace spectrum, there is a need to provide knowledge of the FederalCommunications Commission (FCC) static spectrum allocation pattern andinstantaneous spectrum occupancy patterns of unlicensed bands, as wellas recently opened licensed television (TV) bands to the user'shandset/modem and the access point/gateways. Using this knowledge, thesystem may then make instantaneous decisions to access a particular bandoutside of the licensed cellular spectrum for active communication.

Uplink (UL) and downlink (DL) spectra allocation in a traditionalfrequency division duplex (FDD) licensed cellular spectrum issymmetrical and static. However, spectrum usage in the UL and DL isgenerally asymmetric due to constantly changing usage patterns/trafficdemands, (i.e., FDD), and may have a lightly loaded spectrum in onedirection, (e.g., UL), while a bottleneck in the other (e.g., DL). Forexample, this may occur in a femto cell environment where manyusers/devices access the same spectrum simultaneously and may have highbandwidth requirements. Thus, a fixed/static FDD spectrum allocation isspectrally inefficient and could give rise to bandwidth bottlenecks.

Interference problems may also be encountered between macro cell andfemto cell environments due to the fact that they both operate on thesame spectrum band. There may be two possible ways of overcoming loss inoverall throughput/performance due the interference. One way is toenable aggregation of bandwidth between licensed spectrum bands andother spectrums like TV bands or unlicensed bands. The other way is tohop from the licensed band to another band like TV bands, sub-leasedbands or unlicensed bands, such as industrial, scientific and medical(ISM) bands.

Furthermore, if the cellular operators decide to allow operation in TVwhite space (TVWS) spectrum in femto cells, there would be a need todynamically sense which bands are vacant and also to detect the presenceof wireless microphones and readjust the spectrum usage in such a waythat network operation over the spectrum can still continue by notchingout the piece of spectrum being used by the primary incumbents, such aswireless microphones. For a femto cell environment, multiplesimultaneous users may cause bandwidth bottlenecks, asymmetric trafficpatterns, and varying QoS demands in the UL and DL.

Described herein is a method and apparatus for providing an elasticfrequency division duplex (E-FDD) scheme with corresponding signalingenhancements and associated call flows that provide flexible spectrumusage by using a paired FDD spectrum to enable dynamic access intelevision white space (TVWS), sub-leased spectrum or unlicensedspectrum, (e.g., industrial, scientific and medical (ISM) bands), in afemto cell environment or the like.

FIG. 2 shows an example coverage scenario 200 where a base station 205provides macro cell 210 and a home evolved Node-B (HeNB), for example,provides a femto cell 220. A plurality of WTRUs 225 may operate withinthe macro cell 210 and the femto cell 220 and another plurality of WTRUs230 may operate within the macro cell 210. In a scenario where theoperator in the macro cell 210 uses paired FDD spectrum, the WTRUs 230may move out of the macro cell 210 and into the femto cell 220 where thedensity of WTRUs 225 may be high, as in the case of hot spots. Also, thebandwidth requirement for data usage by the WTRUs 225 may be high, inaddition to the fact that there may be more than one WTRU 225 in thefemto cell 215 with high bandwidth (BW)/QoS requirements. The licensedspectrum over which the femto cell 225 may be operating may quickly runout of resources to support multiple high bandwidth links. Therefore,femto cells may need to operate in bands outside of licensed cellularspectrum like TVWS bands, ISM bands, and the like. This would permit theother spectrum to be used simultaneously with the licensed spectrum inbandwidth aggregation schemes or the other spectrum may be used as analternate spectrum to jump over to when macro-femto interference ishigh.

FIG. 3 shows an example overall architecture 300 of an evolved Node-B(eNodeB) 305 connected to or in communication with a core network 310and a home evolved Node-B (H(e)NB) 315 connected to or in communicationwith the core network 310 via an H(e)NB gateway 320. A WTRU 325 may beconnected to or in communication with the eNodeB 305 and/or the H(e)NB315. The above architecture 300 is one example of an architecture thatmay be used in conjunction with E-FDD as described herein.

FIG. 4 shows an example system 400 of an H(e)NB 405 and a WTRU 410communicating with each other over a single radio access technology(RAT) using an E-FDD duplex scheme. In general, the H(e)NB 405 may havea protocol stack 420 including an Internet Protocol entity 422, a radioresource controller (RRC) 424, a medium access controller 426, and aphysical entity 428. The protocol stack 420 may operate with a widebanddigital transceiver 430 that may have the capability to handle variableduplex spacing, and transmit over multiple spectrum bands simultaneouslyusing a single RAT. The multiple bands, which may be licensed cellularspectrum along with vacant TV bands, sub-leased bands and/or otherunlicensed bands, may be pooled together to provide wide bandwidth forcommunication. The spectrum fragments from TV bands, sub-leased bandsand unlicensed bands are known to be vacant or occupied by accessing awhite space database, or may be inferred from a sensing algorithm usedto actively sense spectrum occupancy patterns. This may be accomplishedusing a sensing entity 440. A cognitive policy engine 445 may provideinformation of the spectrum availability based on information receivedfrom the white space database. The WTRU 410 may have a similararrangement. For example, a protocol stack 450 may include an InternetProtocol entity 452, a radio resource controller 454, a medium accesscontroller 456, and a physical entity 458. The protocol stack 450 mayoperate with a wideband digital transceiver 460, a sensing entity 470and a cognitive policy engine 480 as described herein.

FIG. 5 shows an example protocol stack 500 in the H(e)NB and/or the WTRUthat may access a wide range of spectrum bands. The protocol stack 500may include a radio resource controller 505, a medium access controller510, a physical entity 515 and a wideband digital transceiver 520. Thewideband digital transceiver 520 may be implemented as described in U.S.Patent Publication No. 2010/0226330, filed Mar. 3, 2010, the contents ofwhich is hereby incorporated by reference herein. The initial spectrumused by the system may be the licensed FDD paired spectrum used by thenetwork operator. The wideband digital transceiver 520 may be tuned tothat spectrum and the devices, the H(e)NB and WTRU, may establish a RCCconnection over that spectrum for uninterrupted data transfer.Functionally and/or operationally, an UL FDD band 530 and DL FDD band535 may be moved from high spectrum bands to lower spectrum bands, suchas UL FDD band 540 and DL FDD band 545, using a digital transceiver 515in a WTRU. When the WTRU decides to hop to the new spectrum, a new RRCconnection may be established over the new spectrum bands, and the oldRRC connection is torn down. The wideband digital transceiver 520 maythen be re-tuned to the new spectrum bands. As described herein, the ULand the DL bands of the FDD spectrum may or may not have sufficientduplex spacing for full duplex transmission at the new spectrumlocation.

FIG. 6 shows a licensed spectrum allocation for UL spectrum 605 and DLspectrum 610 in FDD. As stated herein above, in the FDD mode ofcommunication, the frequency spectrum bands have been fixed andstatically allocated to DL and UL. However, the bandwidth requirement onthe UL (DL) may be less than that of the DL (UL). Static allocation ofspectrum for a duplex mode of communication may be wasteful ofbandwidth. In E-FDD, the bandwidth and the exact spectrum bands and/orsubcarriers may be dynamically allocated to the UL and the DL. Thespectrum is not statically assigned to the uplink or downlink. Instead ablock of vacant spectrum may be freely distributed between the twodirections, (i.e., UL and DL), based on instantaneous traffic patternsand bandwidth requirements.

In addition, the spacing between the UL and the DL spectrum may bevariable. In FDD, the spacing between UL and DL spectrum may be verylarge, (in the order of 10s of MHz), to relax the requirement on a radiofrequency (RF) duplexer design. This helps in creating adequate amountof isolation between transmit and receive chains in the modem. In E-FDD,the UL and DL may communicate simultaneously, such as in traditionalFDD, if the spacing between the UL and DL spectrum is greater than athreshold. However, when the spacing is less than the threshold, ahybrid FDD scheme may be used in order to prevent leakage of a transmitchain signal into the receive chain.

In FDD, the UL spectrum may not be as heavily utilized as the DLspectrum. At a minimum, the UL spectrum 705 and DL spectrum 710 and 715in E-FDD may be asymmetrically distributed in the licensed spectrumbased on traffic patterns as shown, for example, in FIG. 7. In otherwords, the UL spectrum, (as shown as UL spectrum 605 in FIG. 6), may besplit such that a part of the spectrum may be utilized for ULcommunication, (i.e., UL spectrum 705), while the remaining part of thespectrum, (i.e., shown as DL spectrum 710), may be aggregated with thelicensed DL spectrum, (i.e., shown as DL spectrum 715), to enhance thecapacity in the DL direction. This may require a low-latency and highaccurate signaling of the instantaneous spectral allocations in eitherdirection between the two wireless nodes communicating with each other.Based on the ability of E-FDD to aggregate or split spectrum based onusage, leasing of unused spectrum to third parties may be possible.

Described herein is spectrum agility for E-FDD. FIGS. 8A-8C show anexample dynamic allocation for UL and DL spectrum based on a trafficpattern. In general, a block of spectrum may be utilized forcommunications in a femto cell. The spectrum may be dynamically assignedby the H(e)NB between the UL and DL based on the instantaneous trafficneeds and the uplink spectrum and the downlink spectrum allocations maynot be of equal bandwidth. For example, in FIG. 8A, UL spectrum 805occupies less bandwidth than DL spectrum 810, but in FIG. 8C, the ULspectrum 825 occupies more bandwidth than DL spectrum 830. FIG. 8B is anexample of UL spectrum 815 and DL spectrum 820 occupying equalbandwidths.

FIG. 9 shows an example of dynamic allocation of spectrum in TVWS in thepresence of a wireless microphone. In existing cellular systems, tooperate in TVWS in either time division duplex (TDD) or FDD mode,communication may need to be completely shut off when a primary usersuch as a wireless microphone is detected. When the H(e)NB operates inTVWS, it has to be aware of the existence of the licensed primary usersof the band, such as wireless microphones, and provide uninterruptedaccess to the spectrum. In this sense, awareness may be achieved usingsensing or a centralized database indicating an occupancy pattern of thespectrum. The spectrum usage pattern using E-FDD mode may look like thespectrum shown in FIG. 9 when a wireless microphone is switched on in aparticular piece of the spectrum. For example, the spectrum allocationmay include an UL spectrum 905, a DL spectrum comprised of DL spectrum910 and 915 and a primary user spectrum 920 that may be a wirelessmicrophone or digital television (DTV) user. If not for the primaryuser, the DL spectrum may include DL spectrum 910, DL spectrum 915 andprimary user spectrum 920. In E-FDD mode, communication between theH(e)NB and the WTRUs may continue regardless of the presence of theprimary user, (i.e., the wireless microphone), and at the same timeavoiding interference with the primary user transmission such as awireless microphone transmission.

Adjacent channel interference between UL and DL spectrum due to smallspectrum gap may be mitigated by either using echo-cancellationtechniques in FDD mode or by using a hybrid FDD (H-FDD) scheme, whereFDD is operated in a time duplexed manner. The H-FDD scheme is favorableto the indoor/home environment where transmit powers are less and thusleakage between transmit and receive chains in the modem may be less.Signaling enhancements may be added to signal the traditional FDD modeor H-FDD mode of operation in the femto cell. Hybrid FDD or half-duplexFDD scheme is a scheme wherein communication on the UL and DL spectrumis in a time multiplexed fashion. The UL and DL spectrum may benon-overlapping and spectrally close to each other, or may be partiallyoverlapping or fully overlapping.

Alternatively, one band of the licensed paired spectrum, either the ULspectrum or DL spectrum, may be moved to TVWS based on interferenceissues and/or additional bandwidth requirements. The amount of TVWSrequired to be used may vary based on QoS requirements, WTRU capabilityand spectrum availability. For example, FIG. 10 shows an example ofmoving an UL spectrum 1010 from a licensed band to a TVWS band 1005 andmaintaining a DL spectrum 1015 as is.

FIG. 11 shows an example of aggregating licensed FDD UL and DL spectrumwith a flexible FDD in TVWS, sub-leased bands or unlicensed bands. Ingeneral, a licensed spectrum allocated for FDD may be aggregated with afragment of unutilized and unlicensed spectrum bands such that a part ofthe unlicensed spectrum is allocated for uplink and aggregated withlicensed uplink spectrum while the remaining part of the unlicensedspectrum is allocated for downlink and aggregated with the licenseddownlink spectrum. In particular, a DL licensed spectrum 1105 is carrieraggregated with a DL unlicensed band spectrum 1115 and an UL licensedspectrum 1110 is carrier aggregated with an UL unlicensed band spectrum1120.

As shown by the examples above, E-FDD provides elastic asymmetricbandwidth provisioning (E-ABP) which adds to the FDD mode,variable/asymmetric bandwidth for UL and DL as described herein aboveand variable duplex spacing between UL and DL as described herein below.In the latter, when spacing is less than a threshold, a communicationsmode may switch from FDD to H-FDD.

Described herein is dynamic swapping of UL and DL bands in E-FDD. As thetransmitter and the receiver may look at the same wide band, both UL andDL spectra may be allocated within the same wide band without need fordifferent radios for each spectrum. This may provide certain advantages.

First, in the presence of a strong out-of-band interferer close to areceiver, the spectral leakage observed in-band may limit the usefulnessof a spectrum fragment spectrally close to the interferer's band.However, the out-of-band leakage observed may be an issue only if theband which is experiencing the leakage is assigned for the WTRU's orH(e)NB's reception. If the band allocation for the UL and DL may beperformed intelligently so that the band experiencing the leakage isassigned to the appropriate link (UL or DL) in FDD, the performanceimpact due to out-of-band leakage may be minimized.

Second, in a multi-antenna adaptive beam forming system, a FDD systemmay be seen to be less efficient than a TDD system because FDD systemsrely on feedback mechanisms between WTRU and the H(e)NB to adjust thebeam pattern. However, the feedback latency itself is in the order of afew milli-seconds, which makes the adaptation less efficient. In a TDDsystem, the channel state feedback, (and thus latency), is eliminatedsince the channel is reciprocal.

To achieve advantages similar to channel reciprocity in TDD systems,E-FDD may dynamically and periodically swap UL and DL spectra so thatboth the WTRU and the H(e)NB may estimate the channel on both spectraand thus eliminate the need for channel state feedback, (andassociated), latency thus making the adaptive beam forming moreefficient in E-FDD systems.

Described herein is variable duplex spacing in E-FDD. In licensedspectrum, the UL and DL spectra are spaced 10s of MHz apart to keep theRF duplexer design simple and cost-effective especially for the WTRU.However, with the wideband digital transceiver, this is not alimitation. The minimum duplex spacing to separate UL and DL spectra maybe a function of cell radius, transmitter output power and the receiversensitivity. The lower the cell radius, the lower the transmit power,and the higher the sensitivity. If the available/vacant spectrum is suchthat UL and DL spectra may not be separated by more than the minimumduplex spacing, then H-FDD may be used, or FDD may be used but withadaptive interference cancellation techniques to adaptively mitigateinterference from the transmit chain into the receive chain. Theadaptive interference cancellation technique may be used to mitigateself-interference generated by leakage of a transmitted signal from thetransmit front-end into the receive front end and may be implemented asan equalizer using algorithms such as normalized least means square(NLMS), Kalman filtering, and the like. Generally this may beimplemented in the digital domain where the self-interference signalexperienced by the receiver front-end may be cancelled by tapping theactual transmitted signal and using the tapped transmission signal as areference signal for the equalization.

FIG. 12 shows full duplex FDD with a DL spectrum band 1205 and a ULspectrum band 1210 sufficiently separated to incur no interference. FIG.13 shows full duplex FDD where a DL spectrum band 1305 and a UL spectrumband 1310 have minimum frequency separation. In this instance H-FDD oradaptive interference cancellation techniques may be used. FIG. 14 showshalf duplex FDD where a DL spectrum band 1405 and a UL spectrum band1410 have less than a minimum frequency separation. FIG. 15 shows fullduplex FDD with adaptive interference cancellation. In the latterinstance, since the UL 1510 and DL 1505 spectrum are spectrally veryclose to each other, this causes spectral leakage from the transmitchain into the receive chain in the transceiver. Thus an adaptiveself-interference cancellation scheme like NLMS algorithm, Kalmanfilter, and the like to equalize/cancel the interference within thetransceiver may help mitigate the self-interference.

Described herein is a high level WTRU reference design architecture.FIG. 16 shows an example high level modem 1600 in a WTRU to supportvariable duplex FDD in E-FDD. The modem 1600 may include an antenna 1605coupled to or in communication with a transmitter/receiver/transceiverfront end 1610. The transmitter/receiver/transceiver front end 1610 isin turn coupled to or in communication with a wideband digital receiver1615, a wideband digital transmitter 1620 and a radio manager 1630. Thewideband digital receiver 1615 and the wideband digital transmitter 1620may be mixed signal components made of analog and digital parts, one forthe transmitter and one for the receiver. The wideband digital receiver1615 may be connected to or be in communication with DL basebandprocessor 1640, the wideband digital transmitter 1620 may be connectedto or be in communication with an UL baseband processor 1645 and theradio manager 1630 may be connected to or be in communication withcontrol signal processors 1650 including MAC processors, RRC processors,a sensing processor and cognitive policy engine.

Described herein is an example implementation of the wide band digitaltransceiver. The transceiver may have a single radio chain for allwaveform types, support continuous bandwidth aggregation, and alsosupport multiple simultaneous links in single band and network. Thepower amplifier may support relatively narrowband transmissions, (singleor multiple adjacent carriers), and may be placed off-chip. The RFfront-end may have a switch-multiplexer for multi-band operation,licensed band/RAT optimized filters, tunable power amplifier outputmatching network and antenna matching network, and tunable notch filterfor reduced WTRU self-jamming.

The transceiver may implement RF functions on digital logic blocks. Theoperating frequency may range or span TVWS band covering from 512-608MHz, (also referred to as the low band), and 614-698 MHz, (also referredto as high band), excluding TV channel #37 which spans 608 to 614 MHz. Asingle board may only cover either a low or high TVWS band at a giventime. Two boards may be needed to cover both the low and the high TVWSbands. The channel spacing may be 6 MHz while the channel raster may be100 kHz. The boards may be programmable as transmitters or receivers inhigh or low TVWS bands, even in operational mode.

The multiple physical chains may be aggregated and share a singlewideband digital transceiver. The mode of operation allows for both TDDand Hybrid FDD although other combinations such as FDD UL and DL may beachieved if two boards are used simultaneously. In FDD operation, fullpower may be used if each board is configured for different TVWS bands.Backed off power may be used if each board is configured for the sameTVWS band by exploiting the antenna separation loss. Synchronizationerror may be less than ±1 μs between the two boards on the same device.Maximum switching time (i.e., Tx to Rx, Rx to Tx) is 1 usec.

Alternatively, E-FDD may be implemented using a tunable RF front endwhere the analog filters and duplexers are tunable in terms of theircarrier frequency. Bandwidth and duplex spacing between uplink anddownlink spectrum and the baseband physical (PHY) algorithms may controlthese exact parameters on the fly.

Described herein is an elastic asymmetric bandwidth provisioning (E-ABP)in E-FDD. In this case, the H(e)NB may operate on TVWS. FIG. 17 shows anexample flowchart 1700 for E-ABP. The H(e)NB may sense a wide range ofspectrum (1705), find vacant spectrum fragments (1710), identify thetotal aggregate bandwidth (UL and DL bandwidth) that should be supportedby the femto cell (1715) and allocate that bandwidth from vacant TVWSfor communication within the femto cell (1720). At start up, the H(e)NBmay use a fixed and symmetric assignment of spectrum on eitherdirection. The spectrum for UL and DL may be common, and shared by allusers in the network. This may be the default spectrum assignment forthe UL and DL, as in the macro cell. As the WTRU moves from the macrocell to the femto cell, the WTRU may connect with the H(e)NB, whichconstantly monitors the traffic patterns and QoS requests in the UL andDL (1725). The RRC layer at the H(e)NB may keep track of traffic/QoSrequirements across the cell and dynamically adjust the bandwidth in theDL and UL, (i.e., it calculates an appropriate ratio of UL bandwidth toDL bandwidth within the fixed total bandwidth to be assigned within thefemto cell) (1730).

The instantaneous assignment of uplink and downlink bandwidths and theexact location of white spaces over a wide range of spectrum aresignaled during the system acquisition phase. Information about thespectrum assignment is signaled on the system information block (SIB)and master information block (MIB) periodically as described below.

Described herein is cellular system acquisition signaling enhancementsfor E-FDD. The MIB may carry the DL bandwidth assignment information.For E-FDD, the MIB may need to be modified with information related toDL spectrum allocation map, i.e., a vector of zeros, (indicatingoccupied fragments), and ones, (indicating vacant fragments), where eachzero or one corresponds to the occupancy of a spectrum fragment. The SIBtype 2 may carry the UL bandwidth information. For E-FDD, the SIB type 2may need to be modified with information related to UL spectrumallocation map, i.e., a vector of zeros and ones, as described herein.

FIGS. 18A and 18B show an example table that indicates parameters thatmay need to be signaled during system acquisition in femto systems toenable E-FDD. The table indicates the message name, description andcomments regarding these parameters. The parameters include, forexample, Master_Slave_mode, Spectrum_frag_length, DL_freq_start,DL_freq_vector, UL_freq_start, UL_freq_vector, Duplex_mode,DL_hop_aggreg_mode, and UL_hop_aggreg_mode.

FIG. 19 shows an example flowchart 1900 for dynamic spectrum allocationfor a wireless communication system employing E-FDD. The wireless systemmay include a regulator/operator database 1905, a base station 1910, aWTRU 1 1915, a WTRU 2 1920 and a WTRU N 1930 (collectively “WTRUs”). Theregulator/operator database 1905 may be a TVWS database as required by agovernment agency such as the Federal Communications Commission or itmay be an operator specific database like a coexistence database tomanage opportunistic use of the spectrum. The base station may be aneNodeB, an H(e)NB, an Access Point and the like. The base station 1910may be in active UL and DL communication on licensed spectrum with anyof the WTRUs (1930). The base station 1910 may determine unlicensedchannel availability (1933) and may send a channel query to theregulator/operator database 1905 (1936). The regulator/operator database1905 may return a channel response to the base station 1910 regardingchannel information and availability (1939). The base station mayperform a sensing operation to determine channel availability (1940).Based on the channel availability information, the base station 1910 mayevaluate and select an unlicensed channel (1942). The selectedunlicensed channel may broadcast the updated spectrum allocation on theMIBs and SIBs to any of the WTRUs. The base station 1910 may now be inactive UL and DL communication on licensed spectrum and/or unlicensedspectrum with any of the WTRUs. Although the term unlicensed may be usedherein, TVWS and/or sub-leased bands may also be used as appropriate.

The base station 1910 and the WTRUs may perform periodic and/oraperiodic sensing on the unlicensed spectrum (1952 and 1955). If nochange in conditions, the base station 1910 remains in active UL and DLcommunication on licensed spectrum and/or unlicensed spectrum with anyof the WTRUs. On the next sensing event (1962 and 1965), the sensing atthe WTRUs may indicate an interference, a primary/secondary userconflict or the like (1967). A sensing report may be sent on the UL tothe base station 1910 by the WTRUs (1970). In response to the sensingreport, the base station 1910 may transmit updated spectrum allocationinformation to the WTRUs using dedicated signaling such as via a MACcontrol element, a RRCConnectionReconfiguration message or the like(1975).

FIG. 20 shows a signaling call flow to enable E-ABP within a cellularnetwork including a WTRU 2005, a base station 2010 and an H(e)NB 2015.The WTRU 2005 may transmit a handover request to the base station 2010(2020), which in turn may transmit an authentication request to theH(e)NB 2015 (2022). The H(e)NB 2015 may then transmit an authenticationresponse to the base station 2010 (2024), which in turn may transmit ahandover response to the WTRU 2005 (2026).

A spectrum_config_setup procedure 2038 may be implemented between theH(e)NB 2015 and the WTRU 2005. The H(e)NB 2015 may transmit the MIB overa broadcast channel (BCH)/physical BCH (PBCH) to the WTRU 2005 and maytransmit SIB type 1, SIB type 2 through SIB type 8 over a downlinkshared channel (DL-SCH)/physical downlink shared channel (PDSCH) (2032,2034, 2036). The WTRU 2005 may transmit data to the H(e)NB 2015 (2040)and the H(e)NB 2015 may transmit data to the WTRU 2005 (2042). TheH(e)NB 2015 may perform a periodic sensing and current trafficassessment procedure (2055). After the periodic spectrum sensing,another spectrum_config_setup procedure (2068) may be implementedbetween the H(e)NB 2015 and the WTRU 2005 using the informationtransmitted by the H(e)NB 2015 to the WTRU 2005 (2060, 2062, 2064,2066). The WTRU 2005 may transmit data to the H(e)NB 2015 (2070) and theH(e)NB 2015 may transmit data to the WTRU 2005 (2072).

FIGS. 21A, 21B and 21C show a table comparing FDD and TDD schemes withthe E-FDD scheme. The comparison is based on seven (7) criteria tocompare the three schemes. As shown in FIG. 21, the E-FDD scheme outperforms in six out of the seven criteria as a multiplexing scheme ascompared to FDD and TDD.

In general, a method of frequency division duplexing (FDD) is describedherein. The method includes assessing spectrum usage for uplink (UL) anddownlink (DL) based on spectrum usage information, determiningavailability of spectrum and dynamically allocating UL spectrum and theDL spectrum from the spectrum in view of spectrum usage assessment andspectrum availability. The spectrum may be licensed, sub-leased,whitespace or unlicensed spectrum. The spectrum usage information may betraffic patterns, bandwidth requirements or quality of servicerequirements and the spectrum availability information may be based onsensing or centralized database access.

The spectrum allocation may be asymmetric and the spacing between the ULspectrum and the DL spectrum may be variable. The UL and the DL maycommunicate simultaneously on a condition that the spacing between theUL spectrum and the DL spectrum is greater than a threshold.Self-interference between a transmit chain and a receive chain due tominimal or no duplex spacing may be mitigated by using one of adaptivecancellation or hybrid FDD (H-FDD). A hybrid FDD scheme may be used toprevent leakage of a transmit chain signal into a receive chain on acondition that spacing between the UL spectrum and the DL spectrum isless than a threshold. Alternatively, an adaptive self-interferencecancellation scheme may be used in the radio frequency (RF) front-end attransmitter and receiver to prevent leakage of the transmit chain signalinto the receive chain on a condition that spacing between the ULspectrum and the DL spectrum is less than a threshold.

Dynamic allocation of available whitespace spectrum may occur in thepresence of a primary user and dynamic allocation of availableunlicensed spectrum may occur in the presence of secondary users. Inparticular, the method further includes detecting the presence of theprimary user on the available whitespace spectrum on a condition thatthe primary user is now using previously available whitespace spectrum,dynamically allocating the UL spectrum and the DL spectrum around theprimary user's transmission in the previously available unlicensedspectrum, and maintaining communication between a base station and atleast one wireless transmit/receive unit regardless of the presence ofthe primary user by avoiding interference with the primary usertransmission.

The UL spectrum and/or the DL spectrum may be moved to at least one of asub-leased, whitespace or unlicensed spectrum due to operationalconditions, where the UL spectrum and the DL spectrum were usinglicensed spectrum. Dynamic swapping between the licensed spectrum and atleast one of sub-leased, whitespace or unlicensed spectrum may occur. Inparticular, the method may include determining at least one ofsub-leased, whitespace or unlicensed channel availability, selecting atleast one of sub-leased, whitespace or unlicensed channel based onbandwidth requirement for the UL and the DL, allocating a selectedsub-leased, whitespace or unlicensed channel, and communicating on anallocated sub-leased, whitespace or unlicensed channel and a licensedchannel. A portion of the UL spectrum or the DL spectrum may beallocated to the remaining one of the DL spectrum or the UL spectrum,respectively. The licensed spectrum may be aggregated with at least oneof sub-leased, whitespace or unlicensed spectrum, where the UL spectrumand the DL spectrum may both include aggregated licensed spectrum andunlicensed spectrum.

Although features and elements are described above in particularcombinations, one of ordinary skill in the art will appreciate that eachfeature or element can be used alone or in any combination with theother features and elements. In addition, the methods described hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer-readable medium for execution by a computeror processor. Examples of computer-readable media include electronicsignals (transmitted over wired or wireless connections) andcomputer-readable storage media. Examples of computer-readable storagemedia include, but are not limited to, a read only memory (ROM), arandom access memory (RAM), a register, cache memory, semiconductormemory devices, magnetic media such as internal hard disks and removabledisks, magneto-optical media, and optical media such as CD-ROM disks,and digital versatile disks (DVDs). A processor in association withsoftware may be used to implement a radio frequency transceiver for usein a WTRU, UE, terminal, base station, RNC, or any host computer.

What is claimed is:
 1. A method of implementing frequency divisionduplex (FDD), the method comprising: assessing spectrum usage for uplink(UL) and downlink (DL) based on spectrum usage information, wherein thespectrum usage information includes quality of service requirements;determining availability of spectrum based on sensing; detecting apresence of a primary user on an available whitespace spectrum on acondition that the primary user is using a previously availablewhitespace spectrum; dynamically allocating the UL spectrum and the DLspectrum from the spectrum around a transmission by the primary user ina previously available unlicensed spectrum in view of spectrum usageassessment and spectrum availability with a variable spacing between theUL spectrum and the DL spectrum; and maintaining communication between abase station and at least one wireless transmit/receive unit by avoidinginterference with the transmission by the primary user.
 2. The method ofclaim 1, wherein the spectrum is at least one of licensed, sub-leased,whitespace or unlicensed spectrum.
 3. The method of claim 1, wherein thespectrum usage information is at least one of traffic patterns orbandwidth requirements.
 4. The method of claim 1, wherein spectrumallocation is asymmetric.
 5. The method of claim 1, further comprisingdetermining the spacing between the UL spectrum and the DL spectrum as afunction of at least one of a cell radius, a transmitter output power,or a receiver sensitivity.
 6. The method of claim 1, wherein the UL andthe DL communicate simultaneously on a condition that spacing betweenthe UL spectrum and the DL spectrum is greater than a threshold.
 7. Themethod of claim 1, wherein a hybrid FDD scheme is used to preventleakage of a transmit chain signal into a receive chain on a conditionthat spacing between the UL spectrum and the DL spectrum is less than athreshold.
 8. The method of claim 1, wherein an adaptiveself-interference cancellation scheme is used in a radio frequency (RF)front-end at transmitter and receiver to prevent leakage of the transmitchain signal into the receive chain on a condition that spacing betweenthe UL spectrum and the DL spectrum is less than a threshold to enablefull duplex FDD.
 9. The method of claim 1, wherein dynamic allocation ofavailable unlicensed spectrum occurs in a presence of secondary users.10. The method of claim 1, wherein self-interference between a transmitchain and a receive chain due to minimal or no duplex spacing ismitigated by using one of adaptive cancellation or hybrid FDD (H-FDD).11. The method of claim 1, further comprising: moving one of the ULspectrum and the DL spectrum to at least one of a sub-leased, whitespaceor unlicensed spectrum due to operational conditions, wherein the ULspectrum and the DL spectrum were using licensed spectrum.
 12. Themethod of claim 1, further comprising: dynamically swapping betweenlicensed spectrum and at least one of sub-leased, whitespace orunlicensed spectrum.
 13. The method claim 1, further comprising:determining at least one of sub-leased, whitespace or unlicensed channelavailability; selecting at least one of sub-leased, whitespace orunlicensed channel based on bandwidth requirement for the UL and the DL;allocating a selected sub-leased, whitespace or unlicensed channel; andcommunicating on an allocated sub-leased, whitespace or unlicensedchannel and a licensed channel.
 14. The method of claim 1, furthercomprising: aggregating licensed spectrum with at least one ofsub-leased, whitespace or unlicensed spectrum, wherein the UL spectrumand the DL spectrum both include aggregated licensed spectrum andunlicensed spectrum.
 15. A wireless communications system, comprising: aprocessor configured to: assess spectrum usage for uplink (UL) anddownlink (DL) based on spectrum usage information, wherein the spectrumusage information includes quality of service requirements; determineavailability of spectrum based on sensing, wherein the spectrum is atleast one of licensed, sub-leased, whitespace or unlicensed spectrum;detect a presence of a primary user on an available whitespace spectrumon a condition that the primary user is using a previously availablewhitespace spectrum; dynamically allocate UL spectrum and DL spectrumfrom the spectrum around a transmission by the primary user in apreviously available unlicensed spectrum in view of spectrum usageassessment and spectrum availability, wherein spacing between the ULspectrum and the DL spectrum is variable; and maintain communicationbetween a base station and at least one wireless transmit/receive unitby avoiding interference with the transmission by the primary user. 16.The wireless communications system of claim 15, wherein the processor isfurther configured to aggregate licensed spectrum with at least one ofsub-leased, whitespace or unlicensed spectrum, wherein the UL spectrumand the DL spectrum both include aggregated licensed spectrum and atleast one of sub-leased, whitespace or unlicensed spectrum.
 17. A methodof implementing frequency division duplex (FDD), the method comprising:assessing spectrum usage for uplink (UL) and downlink (DL) based onspectrum usage information, the spectrum usage information comprisingquality of service requirements; determining availability of spectrumbased on sensing; detecting a presence of a primary user on an availablewhitespace spectrum on a condition that the primary user is using apreviously available whitespace spectrum; dynamically allocating the ULspectrum and the DL spectrum from the spectrum around a transmission bythe primary user in a previously available unlicensed spectrum in viewof spectrum usage assessment and spectrum availability, a portion of oneof the UL spectrum or the DL spectrum being allocated to the remainingone of the DL spectrum or the UL spectrum, respectively; and maintainingcommunication between a base station and at least one wirelesstransmit/receive unit by avoiding interference with the transmission bythe primary user.
 18. The method of claim 17, further comprisingaggregating licensed spectrum with at least one of sub-leased,whitespace or unlicensed spectrum, the UL spectrum and the DL spectrumboth comprising aggregated licensed spectrum and at least one ofsub-leased, whitespace or unlicensed spectrum.
 19. The method of claim17, the spectrum usage information comprising at least one of trafficpatterns or bandwidth requirements.
 20. The method of claim 17, furthercomprising moving one of the UL spectrum and the DL spectrum to at leastone of a sub-leased, whitespace or unlicensed spectrum due tooperational conditions, wherein the UL spectrum and the DL spectrum wereusing licensed spectrum.